I was thinking about that, running the main TBI with all the sensors (map, throttle pos sensor AI temp sensor) then the second one would be just a throttle body with injectors, have a micro switch activate a relay when the second throttle body starts to open and turn the fuel pulse on, the o2 sensor used with TBI is a wideband so it should be able to handle and correct A/F mixture
but this is all to think about, if I make a kit and its successful I will go abit further and see how it goes